Can you try curling it from command line? pretty sure they block icmp on their ELBs.

Is there an http(s) proxy on your network that your browser is configured to send stuff through if so I believe berks supports env vars (at least on *nix) such as https_proxy, https_proxy_user, https_proxy_pass (with the same without the s for non secure connections).

if its not a proxy required scenario can you give us a little information about your setup? Things like network topology might come into play here.